Apparatus for applying coatings to surfaces particularly to the surfaces of flexiblestrip material



Oct. 10, 1933. c. BONAMICO 7 ARPARA'I'US NR APPLYING COATINGS T0 SURFACES PARTICULARLY To ml SURFACES OF FLEXIBLE STRIP MATERIAL Filed larch 8, 1929 2 Sheets-Sheet 1 Oct. 10, 1933. c. BONAMICO 1,929,877

APPARATUS FOR APPLYING COATINGS TO SURFACES PARTICULARLY To TEE SURFACES OF FLEXIBLE STRIP MATERIAL Filed Marsh 8, 1929" 2.Sheets-.heet 2 Patented a. 10, 1933 APPARATUS FOR APPLYING COATINGS T0 SURFACES PARTICULARLY TO THE SUR- FACES 0F FLEXIBLE STRIP MATERIAL Charles Bonamleo, Versailles, France, animosto Harold Wade, London, England- Application March 8; 1929, Serial No; 845,868,

andin Great Britain AW 3, 1928 10 Claiml. (CL 91-43) This invention relates to a method and devices and machines for applying liquid coatings to sheet material, particularly to long strips 0! flexible sheet material, such as celluloid film, cellu 5 lose acetate film and the like. The invention provides a method and devices and machines which enable extremely thin coatings to be applied successiully and which enable liquid coatings containing very volatile constituents and coatings which, in liquid form, are physically unstable, to be successfully used.

According to the invention a method of applying a coating liquid to the surface oil a strip of flexible sheet material is provided which comlike orifice at a pressure substantially equal to that oi the immediate'surroundines oi the orifice passing the flexible material across the orifice and drawing the liquid from the orifice onto the flexible materiel by surface tension of the liquid.

According to one ieature of this invention, a device for applying liquid coatings to surifaces, pcrticularly to the suriaces of long strips of flexihle sheet material, comprises, in combination, a trough, the mouth of which is a narrow slotlike orifice, means for supporting the surface to he coated in close proximity to said orifice but not in contact with the lips thereoi, means ior moving said surface continuously across the oildoe and menus for supplying cootinediquid to the trough in such manner that o meniscus is formed between each lip and the suriace to he coated.

Preierchly the lip on the leading-z" side oi th orifice is nearer to the suriace to he coated than is the lip on the trailing side.

it is iound, in practice, that ii the gen hettueen the trailing lip and the surface to be coated is the some Width throughout the length of the orifice, the meniscus extends further from the ot the centre than near the ends oi the oriilee, the result that the coating tends to he towards the margins oi the surface the centre. According to o further iceoi the invention, the trailing lip oi the orifice so shaped that the gap hetween it and the sinioce to be coated is wider rat the oldie than town-do the ends 01 the orifice. Thus the greater ccpillarity oi the narrower parts of the m esp sense the meniscus at these parts to extend further from the orifice, thereby ten to euuelioe' the thiolmcss oi the resulting coatint; ecross the width 0! the coated surface. The Mp1 lip may be similarly shaped it so do sired.

prises supplying the liquid at the lips of a slot-.

The trough may be provided with a jacket through which a cooling or heating medium can be circulated.-

Preferably, the cross-section of the trough is the same, or'approximately the same, as that of m its orifice throughout its depth, that is to say the walls of which the tree edges tom the aforesaid orifice are flat and parallel to one another.

The orifice is preferably disposed in a horizontal plane with the depth of the trough vertical and the means for supplying coating-liquid thereto comprises a supply-conduit which, together with the trough itself, constitutes a U-tube, and controllable means for supplying coating-liquid to the supply-conduit, whereby 7 the level of the tree surface of the liquid therein may hemaintained at or about the level of the orifice.

According to a further feature of the invention, a coating-machine for continuouslyapplying liquid coatings to flexible sheet material is characterized icy the fact that the sheet material, after coatm, is guided, during the setting or drying of the coating, along e. path which is curved, is convex-3 on the coated side (which side is preferably uppermost) and the chord oi wch is horizontal or epproizirnately so. A heating or cooling radiator may be dis sod along the curved path aioresoid, or along a suhstential part oi it, facing the coated side of the sheet material to and in proximity thereto.

In the accompanying drawings, which illustrete, by way of exple, toms of cootingo chine embodying the above and other features oi the invention,

Figure l is a vertical transverse section on the line l--l oi Figure 2 ol the trough with supply conduit;

Figure is a front elevation on hnlf the scale oi Figure i. of part oi the trough without the to supply conduit;

Figure 3 is o diagr in side elevation oi one form oi complete coating-mace, and

Figure d is a diagram in side elevation oi another iorm of complete coating-=mace.

Referring particularly to his 3 and d, sheet material in the tom of a lone strip 12 is carried on a spool it from which it in led over tensioning'mllers ii to an ehonite oupportingroller or guide 15 about 6 cm. in diameter, around ioo which it passes in a downward loom-that is to say the strip 12 is in contact with the lower side oi the roller 15.

Referring to F1 1 and 2, beneath the supporting-roller 15 is supported a. coatingthe orifice onto the flexible material by surface tension of the liquid.

2. The method of applying an extremely thin coating from a solution of a coating material in a highly volatile solvent upon a moving picture film base comprising supplying the solution to the lips of a slot-like orifice and maintaining the level substantially at the lips by atmospheric pressure, conducting the film base across the orifice out of contact with the lips thereof but sufficiently close to said orifice that the solution forms a meniscus between the lips and the film base and drawing the solution ,onto said film by surface tension of the solution.

3. A method of applying to the surface of a sheet a coating of a liquid of the kind adapted to form a convex meniscus which consists in supplying the liquid to the lips of a narrow slot-like orifice, maintaining the level of the liquid at the.

said lips and substantially constant by atmospheric pressure, traversing the sheet across the orifice in a plane spaced apart from the lips thereof, maintaining a meniscus of the liquid above the lips of the orifice and between the lips and the surface of the sheet and picking up liquid onto the surface of the sheet by surface tension of the liquid.

4. A method of applying to the surface of a long strip of flexible material a coating of a solution of a solid in a volatile solvent which consists in supplying the solution to the lips of a narrow slot-like orifice, maintaining the level of the liquid at the said lips and substantially constant by atmospheric pressure, maintaining a meniscus of the solution above the lips of said orifice and picking up liquid, by surface tension of the liquid, from the meniscus onto the lower surface of the said strip by traversing the same across the orifice incontact with the liquid but in a plane spaced apart from the lips of the orifice.

5. Apparatus for use in applying a coating of a liquid to the surface of a web of sheet material comprising in combination, a guide for the sheet material, a trough for the liquid terminating in a slot-like orifice positioned adjacent to but separated from the said guide and having lips whereof at least one is shaped to be closer to the guide at its ends than its center, means for maintaining a supply of coating liquid at the lips of the orifice and for maintaining the level of the liquid at the orifice substantially constant by atmospheric pressure, and means for traversing the web over the guide through the gap aforesaid out of contact with the lips of the orifice but sumciently close thereto that a meniscus of the liquid may be formed and maintained between said lips and the web.

6. Apparatus for use in applying a coating of a liquid to the surface of a web of sheet material comprising in combination a guide for the sheet material, a trough for the liquid terminating in a slot-like orifice positioned adjacent to but separated from the said guide and having lips one of which is closer to the guide than the other, the latter lip being shaped to be closer to the guideat its ends than at its center, means for maintaining a supply of coating liquid at the lips of the orifice and for maintaining the level of the liquid at the orifice substantially constant by atmospheric pressure, and means for traversing the web over the guide through the gap aforesaid in a direction from the narrower to the wider end thereof in contact with a meniscus of the liquid formed at the lips of the orifice but out of contact with the said lips.

'1. Apparatus for use in applying,'by surface tension of a liquid, 9. solution in that liquid of a coating material to a strip of flexible material comprising in combination, a trough for the solution terminating in a slot-like orifice, means for supporting and guiding said flexible sheet material adjacent to but separated from said orifice, means for maintaining a :supply of solution at the lips of said orifice, and means for maintaining the level of the solution at the orifice substantially constant by atmospheric pressure.

8. Apparatus for use in applying a coating of a liquid, by surface tension of the liquid, to a strip of flexible sheet material comprising, in combination, a guide for the sheet material, a trough for the liquid terminating in a slot-like orifice situated adjacent to but separate from the guide aforesaid and having lips one of which is closer to the guide than the other, means for maintaining by atmospheric pressure a supply of liquid at the orifice at a pressure only sufiicient to maintain a meniscus of the liquid between the orifice and the material supported on the guide, and means for traversing the material over the guide and through the gap between the lips and the guide in a direction from the narrower to the wider end of the gap in contact with the meniscus and out of contact with the lips. I

9. The apparatus as disclosed in claim 7 in which saidtrough is provided with means for heating or cooling the liquid contained therein.

10. The apparatus as disclosed in claim '7 in 

